In the present study, we have improved the sensitivity of the method for detecting microsatellite (STR) polymorphisms, and attempted the detection of the DNA types from a single fingerprint.We conducted at first to improve the sensitivity of the method for detecting STR polymorphisms by PCR. A dual-PCR method and a PEP-PCR method were compared with the ordinary PCR method, and the dual-PCR and the PEP-PCR were approximately ten times as more sensitive than the ordinary PCR. Then, we attempted to detect STR types from fingerprints attached on the surface of objective slides, metal plates (stainless steel), paper sheets and polystyrene sheets. As the results, we were able to detect STR types from a single fingerprint on the surface of those materials by the present dual-PCR method. The Centricon 50 ultrafiltration followed by the silica filter purification was effective for the template preparation before PCR. Aluminum powder or the Ninhydrin reagent used for visualizing fingerprints were not influenced to the present method.次に、ガラス、金属(ステンレス)、紙(上質紙)、プラスチック(ポリスチレン)に実験的に付着させた指紋から、高感度化したPCR法によりSTR多型の検出を試みたところ、Dual-PCR法およびPEP法とDual-PCR法との併用法により1個の指紋からアレルの検出が可能であった。今回試みた指紋からのDNA抽出・精製法の中では、抽出DNAをセントリコン50またはシリカフィルターにより精製した場合に良好な成績が得られた。今回検査したSTR多型3座位の中では、増幅DNA断片長が最も長いCSF1PO座位(299-323bp)の増幅がやや不良であったが、これは指紋から回収されるDNAが低分子化しているためと推測された。なお、指紋の顕出に用いられるアルミニウム粉末、ニンヒドリン試薬は指紋からのSTR多型検出の妨げとはならなかった。